Copyright © (2009) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics
We present room-temperature measurements of high-frequency magnetization fluctuation (mag-noise) in MgO-based nanopillar magnetic tunnel junctions (MTJs) biased with a direct current (DC). In the frequency range of 1-13 GHz, double mag-noise peaks are observed for some MTJs while others only show a single mag-noise peak. The in-plane field dependence of the mag-noise peak frequency is consistent with the Kittel formula. For all MTJs measured, the bias-dependent shift of the mag-noise peak frequency has a pronounced asymmetry. In addition, we find non-monotonic variations in peak linewidth as a function of the external in-plane magnetic field and of the DC bias current. These suggest the possible involvement of non-macrospin modes in spin-torque-dependent thermal mag-noise generation.
By: Y. Guan, D. W. Abraham, M. C. Gaidis, G. Hu, E. J. O'Sullivan, J. J. Nowak, P. L. Trouilloud, D. C. Worledge, J. Z. Sun
Published in: Journal of Applied Physics, volume 105, (no 7), pages art. no. 07D127 in 2009
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